#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

struct cell{
  double x,y,u,v;
  struct mesh *pp,*pm,*mp,*mm;
};
struct mesh{
  double x,y,u,v;
  struct cell *pp,*pm,*mp,*mm;
};
struct param{
  char   runname[80];
  double height, width, cfl, Lx, Ly;
  int    Nx,Ny;
};
extern void input(struct param* in);
extern struct cell* setup(struct param* in); 
extern void output(struct cell* cll, struct param* in);
extern void fir_half(struct cell* cll);
extern void sec_half(struct cell* cll);
extern void full_step(struct mesh* msh);
